"[It's] very foreseeable that they say that they don't care about anything, but we have in history seen that these targeted measures are probably better working sanctions than many other things that you could do," he added.

Bulent Doruk | Anadolu Agency| Getty Images

Russian armed forces stand guard around the Ukrainian military base in the village of Perevalne, 20 km south of Simferopol.

EU leaders agreed on Thursday to expand the bloc's list of people targeted with sanctions over tensions in Ukraine by 12 names, and asked the European Commission to prepare an assessment of the potential impact of broad economic sanctions against Russia.

The EU has already placed sanctions on 21 people, but media reports have said Russian leaders have apparently dismissed their impact.

It was reported by Russian news agency Itar-Tass that Russian Foreign Affairs Committee Deputy Chairman Alexander Romanovich called the U.S. and EU sanctions "absurd and unreal" on Thursday.

"Basically Russia is hurting itself, it's hurting their economy. Investors will leave, they're making their neighbors nervous and they will lose political influence. So this is not the equation for long term stability and a strong Russia," said Reinfeldt, who added that the 12 names to be added to the list were more closely linked to the Russia's invasion of Crimea.

Meanwhile, U.K. Prime Minister David Cameron also told CNBC Asia the EU leaders were in agreement over the need for Russia to be sent a strong message that any further escalation of the conflict would have consequences.

"It's important to send a very clear message that if there is further destabilization in Ukraine then there should be further wide ranging measures taken and we've agreed tonight that we will task the European Commission to draw up those possible measures. That is progress and the world will be able to see that," he added.

The Prime Minister of Finland, Jyrki Katainen, told CNBC he was confident that adding 12 names to the target list would deliver a strong message.

"When looking at the reaction of the oligarchs, it is a strong message. We have two other messages. First of all, we need to get the Russians around the negotiation table and also we need a monetary mission to the Ukraine because we want to avoid expulsion of instability," he added.

Sweden's Reinfeldt also said although the EU needed to demonstrate that it was prepared to get tough on Russia, they did not see this as a long-term solution: "The long-term solution must be an open Europe and open Russia, trading with each other."

Following the summit, the EU also announced that they were considering sending an observer mission to Ukraine if the Organization for Security and Cooperation in Europe fails to put forward its own mission.

On Monday the U.S. announced sanctions on Russian, Ukrainian and Crimean individuals and involved a bank, targeted several individuals close to Putin in retaliation for his military seizure of Ukraine's Crimea region. Putin has since retaliated by imposing sanctions on nine U.S. officials and lawmakers.